Thermodynamic equilibria of vanadium in aqueous systems as applied to the interpretation of the Colorado Plateau ore deposits
Thermodynamic equilibria of vanadium in aqueous systems as applied to the interpretation of the Colorado Plateau ore deposits
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DOI：
10.1016/0016-7037(58)90015-2
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发表时间：
1958-11
影响因子：
5
通讯作者：
H. T. Evans;R. Garrels
中科院分区：
文献类型：
--
作者：
H. T. Evans;R. Garrels
利用所有可用的化学和热力学信息构建了一个图表，显示了已知钒化合物在水平衡中的氧化电位和ph值的稳定性关系。观测到的沉淀条件与根据公布的氧化物自由能计算出的沉淀条件之间的差异，用于估计自然界中发现的水合形式的水化自由能。已确定的钒矿物种类（不包括硅酸盐）根据化学组成、晶体结构和观察到的岩石学组合在平衡图上被指定为稳定区域。矿物图上出现了一个完全自一致的蚀变序列，显示了钒矿石在风化条件下发生的变化。蒙脱石VO（OH）是钒的主要矿物来源。蚀变序列中出现了两条明显的分支：一条局限于含黄铁矿的砂岩中原生氧化钒富集带的酸性条件；另一种发生在方解石普遍存在的更基本的条件下。平衡图被用来得出初步的结论，关于在什么条件下，原来的蒙脱石沉积在砂岩中，可能是通过矿化溶液的作用。
All available chemical and thermodynamic information is utilized to construct a diagram showing the stability relationships of the known vanadium compounds in aqueous equilibrium in terms of oxidation potential and pH. The disparity between the observed precipitation conditions and those calculated from the published free energies of the oxides is used to estimate the free energy of hydration of the hydrated forms found in nature. The well-established vanadium mineral species (not including silicates) are assigned regions of stability on the equilibrium diagram on the basis of chemical constitution, crystal structure and observed petrologic associations. It is found that a completely self-consistent alteration sequence appears on the mineral diagram, showing the changes that occur in the vanadium ores under weathering conditions. Montroseite, VO(OH), is evidently the primary mineral source of vanadium. Two distinct branches appear in the alteration sequence: one is confined to acid conditions characteristic of zones of primary vanadium oxide concentration in the sandstone in the presence of pyrite; and the other occurs in more basic conditions where calcite is common. The equilibrium diagram is used to draw tentative conclusions regarding the conditions under which the original montroseite was deposited in the sandstones, presumably through the action of mineralizing solutions.